Terminal, base station, transmission method, and reception method

ABSTRACT

If repetition transmission is applied to a response signal for a downlink data signal and an uplink signal, the uplink signal is repeatedly transmitted using a certain number of consecutive subframes starting with a first subframe, at which the repetition transmission of the uplink signal starts, and the response signal is repeatedly transmitted using at least the certain number of consecutive subframes starting with a second subframe, at which the repetition transmission of the response signal starts. The first subframe is set to be the same as the second subframe.

BACKGROUND Technical Field

The present disclosure relates to a terminal, a base station, atransmission method, and a reception method.

Description of the Related Art

As a mechanism for supporting a future information society, amachine-to-machine (M2M) communication system that achieves servicesthrough autonomous communication between devices without asking users tomake determinations is expected these years. A smart grid is a specificapplication of the M2M communication system. The smart grid is aninfrastructure system that efficiently supplies a lifeline such aselectricity or gas, and performs M2M communication between a smart meterinstalled in a household or a building and a central server in order toadjust a supply-demand balance of resources autonomously andeffectively. Other applications of the M2M communication system includea monitoring system for article management, distance medicine, or thelike and remote management of stock or charging of vending machines.

In the M2M communication system, in particular, use of cellular systemshaving large communication areas is gaining attention. The 3rdGeneration Partnership Project (3GPP), which is a standardization groupof cellular communication systems, is examining M2M based on a cellularnetwork under a name of machine type communication (MTC) forstandardization of long-term evolution (LTE) and LTE-Advanced. Inparticular, further expansion of communication areas is being examinedin consideration of cases where MTC communication devices such as smartmeters are provided in places such as basements of buildings and are notavailable in existing communication areas (e.g., refer to 3GPP TR 36.888V12.0.0, “Study on provision of low-cost Machine-Type Communications(MTC) User Equipments (UEs) based on LTE,” June 2013). In order tofurther expand the communication areas, for example, repetition, inwhich the same signals are transmitted a plurality of times, is beingexamined.

In a cellular communication system, channels used in uplink, which iscommunication from a terminal to a base station, are a physical uplinkcontrol channel (PUCCH) and a physical uplink shared channel (PUSCH).The PUCCH is a channel for transmitting a response to a downlink datasignal transmitted through a physical downlink shared channel (PDSCH),such as a positive response (acknowledgement (ACK)) or a negativeresponse (negative acknowledgement (NACK)) (hereinafter described as an“ACK/NACK”; also referred to as a “response signal”), and controlinformation such as a scheduling request (SR) indicating a request toassign resources. On the other hand, the PUSCH is a channel fortransmitting data signals. An ACK/NACK, for example, is 1-bitinformation indicating either ACK (no error) or NACK (there is anerror). PUCCH resources used by the terminal to transmit an ACK/NACK andan SR are secured in advance. In the following description, PUCCHresources used for an ACK/NACK will be referred to as “ACK/NACKresources,” and PUCCH resources used for an SR will be referred to as“SR resources.”

TRANSMISSION OF ACK/NACK AND SR

In Release 11 (hereinafter referred to as “Rel. 11”) of LTE, iftransmission of a PUSCH is not assigned to the same subframe as one inwhich an ACK/NACK is transmitted, the ACK/NACK is transmitted throughthe PUCCH. In addition, for example, a signal point of binaryphase-shift keying (BPSK) is used for an ACK/NACK, and an ACK istransmitted using a signal point of −1, and a NACK is transmitted usinga signal point of +1.

FIG. 1 illustrates an example of transmission of an ACK/NACK and an SRusing PUCCH resources in Rel. 11. “Information to be transmitted”illustrated in FIG. 1 indicates a signal to be transmitted in eachsubframe, and “A/N” indicates an ACK/NACK (the same holds in thesubsequent drawings).

As illustrated in FIG. 1, if an SR is not transmitted in the samesubframe as one in which an ACK/NACK is transmitted, the ACK/NACK istransmitted using an ACK/NACK resource. On the other hand, iftransmission of an SR occurs in the same subframe as one in which anACK/NACK is transmitted, the ACK/NACK is transmitted using an SRresource. In addition, in a subframe in which only transmission of an SRoccurs, the SR is transmitted using an SR resource. If only an SR istransmitted, the SR is transmitted using a signal point of +1 (the samesignal point as a NACK) in BPSK (e.g., refer to 3GPP TS 36.211 V11.5.0,“Physical channels and modulation (Release 11),” December 2013).

A base station identifies, through blind detection such as a powerdetermination, a resource (an ACK/NACK resource or an SR resource) withwhich an ACK/NACK is transmitted. If determining that the ACK/NACK hasbeen transmitted using an SR resource, the base station determines thatthere is an SR and decodes the ACK/NACK using a signal of the SRresource. On the other hand, if determining that the ACK/NACK has beentransmitted using an ACK/NACK resource, the base station determines thatthere is no SR and decodes the ACK/NACK using a signal of the ACK/NACKresource. In addition, if detecting a signal of an SR resource at atiming other than timings (known timings) at which ACK/NACKs arereceived in response to downlink data signals, the base stationdetermines that there is an SR.

TRANSMISSION OF ACK/NACK AND PUSCH

In Rel. 11, if transmission of a PUSCH is assigned to the same subframeas one in which an ACK/NACK is transmitted, the ACK/NACK is transmittedthrough the PUSCH.

FIG. 2 illustrates an example of transmission of a PUSCH and an ACK/NACKin Rel. 11. In “information to be transmitted” illustrated in FIG. 2,“Data” indicates an uplink data signal (hereinafter also referred tosimply as “data”) (the same holds in the subsequent drawings).

As illustrated in FIG. 2, in a subframe in which only an ACK/NACK istransmitted, the ACK/NACK is transmitted using an ACK/NACK resource. Inaddition, in a subframe only data is assigned, the data is transmittedusing a PUSCH.

In addition, as illustrated in FIG. 2, if data is assigned to the samesubframe as one in which an ACK/NACK is transmitted, the ACK/NACK istime-multiplexed with a data signal and transmitted in a PUSCH. Morespecifically, by puncturing part of a data signal mapped in a resourceadjacent to a reference signal (RS), the ACK/NACK is arranged in theresource for that part (e.g., refer to 3GPP TS 36.212 V11.4.0,“Multiplexing and channel coding (Release 11),” December 2013).

The base station determines whether an ACK/NACK is included in areceived PUSCH through blind detection. Here, the base station candetect a timing at which an ACK/NACK is transmitted in response to adownlink data signal (PDSCH) on the basis of assignment of the downlinkdata signal in a physical downlink control channel (PDCCH). The basestation can therefore decode the PUSCH while assuming that an ACK/NACKis included, without performing blind detection in a subframe in whichthe terminal must transmit the ACK/NACK. Due to the following reason,however, the base station determines presence or absence of an ACK/NACKthrough blind detection. If the terminal fails to receive a PDCCH withwhich the terminal is notified of assignment of a downlink data signal,the terminal does not transmit an ACK/NACK but transmits only a datasignal using a PUSCH. At this time, the PUSCH includes only the datasignal, but if the base station decodes the PUSCH while assuming thatthe PUSCH includes an ACK/NACK, data signal decoding propertiesdeteriorate. The base station therefore, initially needs to determinewhether an ACK/NACK is included.

REPETITION

In Rel. 11, ACK/NACK repetition in the PUCCH in which the maximum numberof repetitions is six is introduced. FIG. 3 illustrates an example ofACK/NACK repetition and SR transmission in PUCCH resources in Rel. 11.

An ACK/NACK repetition is transmitted using ACK/NACK resources securedin advance. In addition, as illustrated in FIG. 3, if transmission of anSR occurs in the same subframe as one in which transmission of anACK/NACK repetition, priority is given to the transmission of theACK/NACK repetition using an ACK/NACK resource, and the SR is dropped(not transmitted) (e.g., refer to 3GPP TS 36.213 V11.5.0, “Physicallayer procedures (Release 11),” December 2013).

BRIEF SUMMARY

In order to achieve the above-described further expansion of thecommunication areas, introduction of repetition is closely examined inLTE-Advanced Release 12 (hereinafter referred to as “Rel. 12”) andlater. Although ACK/NACK repetition is specified in Rel. 11, the numberof repetitions is desired to be increased in order to further expand thecommunication areas. In addition, SR repetition and PUSCH repetition,which are not conducted in Rel. 11, are also effective.

Details of a case in which repetition transmission is applied to aplurality of signals such as an ACK/NACK, an SR, and a PUSCH, however,have not yet been examined.

One non-limiting and exemplary embodiment provides a terminal, a basestation, a transmission method, and a reception method capable ofavoiding deterioration of signal reception properties (decodingproperties, detection properties, and the like) when repetitiontransmission is applied to at least two of an ACK/NACK, an SR, and aPUSCH.

In one general aspect, the techniques disclosed here feature a terminalincluding a receiver that receives information indicating a firstsubframe at which repetition transmission of an uplink signal starts anda second subframe at which repetition transmission of a response signalfor a downlink data signal starts, and a transmitter that repeatedlytransmits the uplink signal using a certain number of consecutivesubframes starting with the first subframe and the response signal usingat least the certain number of consecutive subframes starting with thesecond subframes. The first subframe is set to be the same as the secondsubframe.

According to an aspect of the present disclosure, deterioration ofsignal reception properties can be avoided when repetition transmissionis applied to at least two of an ACK/NACK, an SR, and a PUSCH.

It should be noted that these general or specific aspects may beimplemented as a system and a computer program, or may be implemented asan arbitrary combination of a system, an apparatus, a method, and acomputer program.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates an example of transmission of an ACK/NACK and an SRin a PUCCH;

FIG. 2 illustrates an example of transmission of an ACK/NACK and data;

FIG. 3 illustrates an example of repetition transmission of an ACK/NACKin the PUCCH;

FIGS. 4A and 4B illustrate a problem at a time when repetitiontransmission of an ACK/NACK and an SR is performed;

FIG. 5 illustrates a problem at a time when repetition transmission ofan ACK/NACK and data is performed;

FIG. 6 illustrates essential components of a base station according to afirst embodiment of the present disclosure;

FIG. 7 illustrates essential components of a terminal according to thefirst embodiment of the present disclosure;

FIG. 8 illustrates the configuration of the base station according tothe first embodiment of the present disclosure;

FIG. 9 illustrates the configuration of the terminal according to thefirst embodiment of the present disclosure;

FIG. 10 illustrates timings of repetition transmission of an ACK/NACKand an SR according to the first embodiment of the present disclosure;

FIG. 11 illustrates timings of repetition transmission of an ACK/NACKand data according to a second embodiment of the present disclosure;

FIG. 12 illustrates timings of repetition transmission of an ACK/NACKand an SR according to a third embodiment of the present disclosure;

FIG. 13 illustrates parameters used for calculating start positions ofSR repetition transmission according to the third embodiment of thepresent disclosure;

FIG. 14 illustrates timings of repetition transmission of an ACK/NACKand data according to a fourth embodiment of the present disclosure;

FIG. 15 illustrates a problem at a time when repetition transmission ofan ACK/NACK and an SR according to a fifth embodiment of the presentdisclosure is performed;

FIG. 16 illustrates timings of repetition transmission of an ACK/NACKand an SR according to the fifth embodiment of the present disclosure;

FIG. 17 illustrates a problem at a time when repetition transmission ofan ACK/NACK and data according to a sixth embodiment of the presentdisclosure is performed; and

FIG. 18 illustrates timings of repetition transmission of an ACK/NACKand data according to the sixth embodiment of the present disclosure.

DETAILED DESCRIPTION Understanding Forming Basis of Present Disclosure

First, a problem that can arise when repetition transmission is appliedto a plurality of signals such as an ACK/NACK, an SR, and a PUSCH willbe described.

Problem in Transmission of ACK/NACK and SR in PUCCH

FIGS. 4A and 4B illustrate examples of ACK/NACK repetition transmissionand SR repetition transmission in the PUCCH.

If ACK/NACK repetition transmission and SR repetition transmission areperformed in the PUCCH, the SR repetition transmission might occurduring the ACK/NACK repetition transmission as illustrated in FIGS. 4Aand 4B.

At this time, in a method (refer to FIG. 3) in which priority is givento the ACK/NACK repetition transmission as in Rel. 11, an SR in the samesubframe as one in which an ACK/NACK is transmitted is dropped asillustrated in FIG. 4A, and a necessary number of SRs (four subframes inFIG. 4A) are not transmitted, thereby deteriorating SR detectionproperties in a base station.

On the other hand, if transmission of an SR occurs in the same subframeas one in which an ACK/NACK is transmitted, a method may be used inwhich the ACK/NACK is transmitted using an SR resource (refer to FIG.1). In this method, however, as illustrated in FIG. 4B, resources usedfor transmitting ACK/NACKs might change from ACK/NACK resources to SRresources during the ACK/NACK repetition. Furthermore, the base stationneeds to identify, through blind detection such as a powerdetermination, resources used for transmitting the ACK/NACKs, but inthis method, the base station is likely to be unable to determinewhether an SR is transmitted until all of repeatedly transmitted SRs arereceived. As a result, an accuracy of determining resources used fortransmitting the ACK/NACKs might deteriorate, thereby deterioratingACK/NACK decoding properties.

In addition to the case described with reference to FIGS. 4A and 4B inwhich “SR repetition transmission occurs during ACK/NACK repetitiontransmission,” a case in which “ACK/NACK repetition transmission occursduring SR repetition transmission” (not illustrated) is possible. Inthis case, the base station can decode ACK/NACKs after receiving all ofrepeatedly transmitted SRs. A signal point of SR resources, however,might change during the SR repetition transmission because signalstransmitted using the SR resources change from SRs to ACK/NACKs duringthe SR repetition transmission. As a result, in-phase combination cannotbe performed at a time of detection of the SRs, and the SR detectionproperties might deteriorate.

Problem in Transmission of ACK/NACK and Data in PUSCH

FIG. 5 illustrates an example of ACK/NACK repetition transmission andPUSCH repetition transmission.

If ACK/NACK repetition transmission and PUSCH repetition transmissionare performed, the ACK/NACK repetition transmission might occur duringthe PUSCH repetition transmission as illustrated in FIG. 5. At thistime, in a subframe in which an ACK/NACK and a PUSCH (data signal) areassigned, a method may be used in which the data signal and the ACK/NACKare time-multiplexed with each other and transmitted in a PUSCH (referto FIG. 2).

In this method, however, a signal in the PUSCH might change from asignal including only data to a signal in which data and an ACK/NACK aretime-multiplexed with each other during the PUSCH repetitiontransmission. The base station needs to determine whether an ACK/NACK isincluded through blind detection. The base station, however, is likelyto be unable to determine whether an ACK/NACK is included in a PUSCHuntil a signal including data and an ACK/NACK is received the number ofrepetitions of an ACK/NACK (four subframes in FIG. 5).

If content of a signal in a PUSCH changes during the PUSCH repetitiontransmission, therefore, an accuracy of determining whether an ACK/NACKis included in a PUSCH might deteriorate in het base station, therebydeteriorating the ACK/NACK decoding properties and PUSCH data decodingproperties.

In addition to the case described with reference to FIG. 5 in which“ACK/NACK repetition transmission occurs during PUSCH repetitiontransmission,” a case in which “PUSCH repetition transmission occursduring ACK/NACK repetition transmission” is possible. In this case, too,the same problem as above arises.

On the basis of the above knowledge, embodiments of the presentdisclosure will be described in detail hereinafter with reference to thedrawings. In the embodiments, the same components are given the samereference numerals.

Overview of Communication System

In the following description, an frequency division duplex (FDD) systemwill be taken as an example.

In addition, a communication system according to each embodiment of thepresent disclosure is a system according to LTE-Advanced, for example,and includes a base station 100 and a terminal 200.

When transmitting an ACK/NACK, an SR, and a PUSCH, the terminal 200applies repetition transmission to at least two of the ACK/NACK, the SR,and the PUSCH. When performing the repetition transmission, the terminal200 repeatedly transmits each signal in consecutive subframescorresponding to a certain number of repetitions (repetition factor).

FIG. 6 is a block diagram illustrating essential components of the basestation 100 according to each embodiment of the present disclosure. Inthe base station 100 illustrated in FIG. 6, a setting unit 101 generatescontrol information (timing information) for identifying a firstsubframe (start position) at which repetition transmission of an uplinksignal (an SR or an uplink data signal) starts and a second subframe(start position) at which repetition transmission of a response signal(ACK/NACK) for a downlink data signal starts. A reception unit 109receives, from the terminal 200 to which the control information hasbeen transmitted, an uplink signal repeatedly transmitted using acertain number of consecutive subframes starting with the first subframeand a response signal repeatedly transmitted using at least the certainnumber of consecutive subframes starting with the second subframe. It isto be noted that the first subframe (start position) of the repetitiontransmission of the uplink signal (the SR or the uplink data signal) isset to be the same as the second subframe (start position) for theACK/NACK repetition transmission. The “setting subframes (startpositions) to be the same” refers to setting the same subframes (timeresources) (the start positions are temporally identical). In addition,if a plurality of first subframes and a plurality of second subframesare set, the “setting subframes (start positions) to be the same” refersto setting each of the plurality of first subframes to be the same asone of the plurality of second subframes.

FIG. 7 is a block diagram illustrating essential components of theterminal 200 according to each embodiment of the present disclosure. Inthe terminal 200 illustrated in FIG. 7, a setting information receptionunit 209 receives information indicating a first subframe (startposition) at which repetition transmission of an uplink signal (an SR oran uplink data signal) starts and a second subframe (start position) atwhich repetition transmission of a response signal (ACK/NACK) for adownlink data signal starts. A transmission unit 213 repeatedlytransmits the uplink signal using a certain number of consecutivesubframes starting with the first subframe and the response signal usingat least the certain number of consecutive subframes starting with thesecond subframe.

First Embodiment Configuration of Base Station

FIG. 8 is a block diagram illustrating the configuration of the basestation 100 according to a first embodiment of the present disclosure.In FIG. 8, the base station 100 includes the setting unit 101, a codingunit 102, a modulation unit 103, a control information generation unit104, a signal assignment unit 105, an orthogonal frequency-divisionmultiplexing (OFDM) signal generation unit 106, a transmission unit 107,an antenna 108, the reception unit 109, a fast Fourier transform (FFT)unit 110, a PUSCH demodulation unit 111, a PUCCH extraction unit 112, aPUCCH demodulation unit 113, and an ACK/NACK decoding unit 114.

The setting unit 101 generates timing information regarding subframes(hereinafter referred to as “start positions”) at which repetitiontransmission of at least two of an ACK/NACK, an SR, and a PUSCH startsin the terminal 200. The timing information may be assigned to a PDCCHand transmitted to the terminal 200, or may be transmitted to theterminal 200 in a semi-static manner as a higher layer control signal(radio resource control (RRC)). If the timing information is assigned toa PDCCH and transmitted to the terminal 200, the setting unit 101outputs the timing information to the control information generationunit 104. If the timing information is transmitted as a higher layercontrol signal, the setting unit 101 outputs the timing information tothe coding unit 102. Details of a method for setting start positions ofrepetition transmission used by the setting unit 101 will be describedlater.

The coding unit 102 performs error correction coding, such as turbocoding, on transmission data (a bit sequence, that is, a downlink datasignal) and outputs a resultant coded bit sequence to the modulationunit 103.

The modulation unit 103 performs a data modulation process on the codedbit sequence received from the coding unit 102 and outputs a resultantdata modulation signal to the signal assignment unit 105.

The control information generation unit 104 generates controlinformation to be assigned to a PDCCH, performs a coding and modulationprocess on the control information, and outputs a resultant controlinformation modulation signal to the signal assignment unit 105.

The signal assignment unit 105 maps a data modulation signal receivedfrom the modulation unit 103 in a downlink data signal assignmentresource and outputs the mapped signal to the OFDM signal generationunit 106. In addition, the signal assignment unit 105 maps the controlsignal modulation signal received from the control informationgeneration unit 104 in a downlink control information assignmentresource and outputs the mapped signal to the OFDM signal generationunit 106.

The OFDM signal generation unit 106 performs subcarrier mapping and aninverse fast Fourier transform (IFFT) process on the signals receivedfrom the signal assignment unit 105 to generate a time-domain OFDMsignal. The OFDM signal generation unit 106 outputs the generated OFDMsignal to the transmission unit 107.

The transmission unit 107 performs an radio frequency (RF) process suchas digital-to-analog (D/A) conversion or up-conversion on the OFDMsignal received from the OFDM signal generation unit 106 and transmits aradio signal to the terminal 200 through the antenna 108.

The reception unit 109 performs an RF process such as down-conversion orA/D (Analog-to-Digital) conversion on a radio signal received from theterminal 200 through the antenna 108 and outputs a resultant basebanddiscrete Fourier transform-spread-orthogonal frequency-divisionmultiplexing (DFT-S-OFDM) signal to the FFT unit 110. The receivedDFT-S-OFDM signal includes an ACK/NACK, an SR, or a PUSCH subjected torepetition transmission.

The FFT unit 110 converts the DFT-S-OFDM signal received from thereception unit 109 into a frequency-domain signal by performing an FFTprocess. The FFT unit 110 outputs the resultant frequency-domain signalto the PUSCH demodulation unit 111 and the PUCCH extraction unit 112.

The PUSCH demodulation unit 111 extracts a PUSCH from the signalreceived from the FFT unit 110 and demodulates the extracted PUSCH. Morespecifically, the PUSCH demodulation unit 111 determines whether thePUSCH includes an ACK/NACK through a blind determination. If determiningthat an ACK/NACK is not included, the PUSCH demodulation unit 111demodulates a data signal and performs an error correction process suchas turbo coding and an error detection process such as a CRCdetermination to obtain reception data. On the other hand, ifdetermining that an ACK/NACK is included, the PUSCH demodulation unit111 separates a data signal and the ACK/NACK from each other, outputsthe ACK/NACK signal to the ACK/NACK decoding unit 114, and performs theabove processes on the data signal to obtain reception data.

The PUCCH extraction unit 112 extracts a PUCCH from the signal receivedfrom the FFT unit 110 and outputs the extracted PUCCH to the PUCCHdemodulation unit 113.

The PUCCH demodulation unit 113 demodulates the PUCCH received from thePUCCH extraction unit 112. More specifically, the PUCCH demodulationunit 113 identifies, through blind detection such as a powerdetermination, a resource (an ACK/NACK resource or an SR resource) usedfor transmitting the ACK/NACK. If determining that the ACK/NACK has beentransmitted using an SR resource, the PUCCH demodulation unit 113determines that there is an SR and outputs the ACK/NACK to the ACK/NACKdecoding unit 114. In addition, if determining that the ACK/NACK hasbeen transmitted using an ACK/NACK resource, the PUCCH demodulation unit113 determines that there is no SR and outputs the ACK/NACK to theACK/NACK decoding unit 114. In addition, if determining that only an SRhas been transmitted using an SR resource, the PUCCH demodulation unit113 determines that there is an SR.

The ACK/NACK decoding unit 114 performs a decoding process on theACK/NACK received from the PUSCH demodulation unit 111 or the PUCCHdemodulation unit 113 to obtain a reception ACK/NACK (an ACK or a NACK).The obtained reception ACK/NACK is used by a retransmission control unit(not illustrated) to determine whether to retransmit a correspondingdownlink data signal or transmit new data.

Configuration of Terminal

FIG. 9 is a block diagram illustrating the configuration of the terminal200 according to the first embodiment of the present disclosure. In FIG.9, the terminal 200 includes an antenna 201, a reception unit 202, ademodulation unit 203, a decoding unit 204, a coding unit 205, amodulation unit 206, an ACK/NACK generation unit 207, an SR generationunit 208, the setting information reception unit 209, a control channelformation unit 210, an ACK/NACK multiplexing unit 211, a DFT-S-OFDMsignal generation unit 212, and the transmission unit 213.

The reception unit 202 performs an RF process such as down-conversion orAD conversion on a radio signal received from the base station 100through the antenna 201 to obtain a baseband OFDM signal. The receptionunit 202 outputs the OFDM signal to the demodulation unit 203. Inaddition, the reception unit 202 outputs a PDCCH including timinginformation for identifying start positions of a plurality ofconsecutive subframes used for repetition transmission of at least twoof an ACK/NACK, an SR, and a PUSCH in the OFDM signal or a higher layercontrol signal to the setting information reception unit 209.

The demodulation unit 203 performs a demodulation process on the OFDMsignal received from the reception unit 202, extracts data (downlinkdata signal), and outputs the data to the decoding unit 204.

The decoding unit 204 performs an error correction process such as turbodecoding and an error detection process such as a cyclic redundancycheck (CRC) determination on the data received from the demodulationunit 203. The decoding unit 204 outputs an obtained result of the errordetection to the ACK/NACK generation unit 207.

The coding unit 205 performs error correction coding such as turbocoding on transmission data (a bit sequence, that is, an uplink datasignal) and outputs a resultant coded bit sequence to the modulationunit 206.

The modulation unit 206 performs a data modulation process on the codedbit sequence received from the coding unit 205 and outputs a resultantdata modulation signal to the ACK/NACK multiplexing unit 211.

The ACK/NACK generation unit 207 generates an ACK/NACK on the basis ofthe result of the error detection received from the decoding unit 204.More specifically, if an error is detected, the ACK/NACK generation unit207 generates an ACK, and if an error is not detected, the ACK/NACKgeneration unit 207 generates a NACK. The ACK/NACK generation unit 207outputs the generated ACK/NACK to the control channel formation unit210.

If a scheduling request to the base station 100 occurs, the SRgeneration unit 208 generates an SR signal and outputs the SR signal tothe control channel formation unit 210.

The setting information reception unit 209 reads the timing informationreceived from the reception unit 202. The setting information receptionunit 209 then sets, in accordance with read transmission timings,subframes (start positions) at which repetition transmission of at leasttwo of an ACK/NACK, an SR, and a PUSCH starts and outputs the subframesto the control channel formation unit 210 and the ACK/NACK multiplexingunit 211.

The control channel formation unit 210 secures certain PUCCHtransmission resources and identifies in advance the timings (subframesthat are candidates for start positions) of repetition transmission ofan ACK/NACK and an SR received from the setting information receptionunit 209. The control channel formation unit 210 forms a PUCCH fortransmitting control information including an ACK/NACK and/or an SRusing a certain format in accordance with the timings of repetitiontransmission of an ACK/NACK and an SR received from the settinginformation reception unit 209 depending on cases such as independenttransmission of an ACK/NACK, independent transmission of an SR, andsimultaneous transmission of an ACK/NACK and an SR. In addition, iftransmission of an ACK/NACK and transmission of a PUSCH (uplink datasignal) occur in the same subframe, the control channel formation unit210 outputs the ACK/NACK to the ACK/NACK multiplexing unit 211 withoutincluding the ACK/NACK in a PUCCH. The control channel formation unit210 outputs the formed PUCCH to the DFT-S-OFDM signal generation unit212.

The ACK/NACK multiplexing unit 211 identifies in advance the timings(subframes that are candidates for start positions) of repetitiontransmission of an ACK/NACK and a PUSCH received from the settinginformation reception unit 209. The ACK/NACK multiplexing unit 211 formsa PUSCH on the basis of a certain format in accordance with the timingsof repetition transmission of an ACK/NACK and a PUSCH received from thesetting information reception unit 209 depending on cases such asindependent transmission of data and simultaneous transmission of anACK/NACK and data. The ACK/NACK multiplexing unit 211 outputs the formedPUSCH to the DFT-S-OFDM signal generation unit 212.

The DFT-S-OFDM signal generation unit 212 performs a DFT process,subcarrier mapping, and an IFFT process on the PUCCH received from thecontrol channel formation unit 210 or the PUSCH received from theACK/NACK multiplexing unit 211 to generate a time-domain DFT-S-OFDMsignal. The DFT-S-OFDM signal generation unit 212 outputs the generatedDFT-S-OFDM signal to the transmission unit 213.

The transmission unit 213 performs an RF process such as D/A conversionor up-conversion on the DFT-S-OFDM signal received from the DFT-S-OFDMsignal generation unit 212 and transmits a radio signal to the basestation 100 through the antenna 201. In doing so, at least two of anACK/NACK, an SR, and a PUSCH are repeatedly transmitted using aplurality of consecutive subframes starting from a start position of therepetition transmission read by the setting information reception unit209.

Operation of Base Station 100 and Terminal 200

The operation of the base station 100 and the terminal 200 having theabove configurations will be described. It is to be noted that ACK/NACKrepetition transmission and SR repetition transmission through the PUCCHwill be described hereinafter.

In the following description, the number of repetitions of an ACK/NACKand the number of repetitions of an SR are the same.

The base station 100 sets, for the terminal 200, subframes (candidatesfor start positions) at which the ACK/NACK repetition transmissionstarts and subframes (candidates for start positions) at which the SRrepetition transmission starts. More specifically, the base station 100matches the start positions of the SR repetition transmission with thestart positions of the ACK/NACK repetition transmission. That is, thebase station 100 sets each of the start positions of the SR repetitiontransmission to the same subframe for one of the start positions of theACK/NACK repetition transmission. It is to be noted that the basestation 100 may set the start positions of the SR repetitiontransmission to the same subframes for all the start positions of theACK/NACK repetition transmission.

The base station 100 (setting unit 101) then transmits timinginformation for identifying the set start positions of the ACK/NACKrepetition transmission and the set start positions of the SR repetitiontransmission to the terminal 200, for example, through higher layersignaling.

For example, the base station 100 performs assignment (e.g., DLassignment) of a downlink data signal corresponding to an ACK/NACK. Theterminal 200 can identify a subframe a certain number of subframes aftera subframe in which the assignment of the downlink data signal has beenreceived as a transmission timing of the ACK/NACK for the downlink datasignal. As the timing information, therefore, existing controlinformation indicating the assignment of the downlink data signal may beused, instead. In this case, the terminal 200 may identify the startpositions of the ACK/NACK repetition transmission on the basis of thetiming information (the assignment of the downlink data signal: theexisting control information) and set part or all of the start positionsof the ACK/NACK repetition transmission as the start positions of the SRrepetition transmission. The signaling for setting the start positionsof the SR repetition transmission, therefore, becomes unnecessary.

Alternatively, the base station 100 may set the start positions of theSR repetition transmission and transmit timing information indicatingthe setting to the terminal 200. In this case, the terminal 200 may setthe transmitted start positions of the SR repetition transmission as thestart positions of the ACK/NACK repetition transmission. Alternatively,the base station 100 may set arbitrary subframes as the start positionsof the ACK/NACK and SR repetition transmission and transmit timinginformation indicating the setting to the terminal 200.

The terminal 200 (setting information reception unit 209) receives thetiming information transmitted from the base station 100 and sets thestart positions (subframes) of the ACK/NACK and SR repetitiontransmission. The terminal 200 (transmission unit 213) then repeatedlytransmits an ACK/NACK using consecutive subframes, which correspond to acertain number of repetitions, starting with a subframe that is a startposition of the ACK/NACK repetition transmission and an SR usingconsecutive subframes, which correspond to a certain number ofrepetitions, starting with a subframe that is a start position of the SRrepetition transmission.

FIG. 10 illustrates an example of transmission timings of ACK/NACKs andSRs. It is to be noted that in FIG. 10, the number of repetitions of anACK/NACK and an SR is four (four subframes) each.

As illustrated in FIG. 10, in a subframe in which only an ACK/NACK istransmitted, the terminal 200 transmits the ACK/NACK using an ACK/NACKresource. In addition, in a subframe in which only an SR is transmitted,the terminal 200 transmits the SR using an SR resource.

In addition, as illustrated in FIG. 10, if ACK/NACK repetitiontransmission and SR repetition transmission occur in the same subframes,the terminal 200 transmits ACK/NACKs using SR resources.

Here, the terminal 200 (setting information reception unit 209) setseach of start positions of the SR repetition transmission to the samesubframe for one of start positions of the ACK/NACK repetitiontransmission. That is, as illustrated in FIG. 10, the start positions ofthe SR repetition transmission are at least the same as the startpositions of the ACK/NACK repetition transmission.

In addition, as illustrated in FIG. 10, the number of repetitions of anACK/NACK and an SR is the same, namely four subframes.

If ACK/NACK repetition transmission and SR repetition transmission occurin the same subframes, therefore, subframes used for the ACK/NACKrepetition transmission and subframes used for the SR repetitiontransmission are the same. That is, if ACK/NACK repetition transmissionand SR repetition transmission occur in the same subframes, the terminal200 transmits ACK/NACKs using SR resources in all subframes in a periodof the ACK/NACK and SR repetition transmission. In other words, inconsecutive subframes (four consecutive subframes in FIG. 10) in aperiod of the SR repetition transmission, resources used fortransmitting the ACK/NACKs do not switch in midstream as in FIGS. 4A and4B.

As described above, according to the present embodiment, since theresources for transmitting the ACK/NACKs do not change in the period ofthe SR repetition transmission as in FIG. 4B, the base station 100 candecode the ACK/NACKs after receiving all of repeatedly transmitted SRsand determining whether the SRs have been transmitted. As a result,deterioration of the ACK/NACK decoding properties can be avoided.

Furthermore, according to the present embodiment, since the resourcesused for transmitting the ACK/NACKs do not change in the period of theSR repetition transmission, a signal point of the SR resources does notchange during the SR repetition transmission. In-phase combination cantherefore be performed at a time of detection of the SRs, therebyimproving the SR detection properties.

In addition, if ACK/NACK repetition transmission and SR repetitiontransmission occur in the same subframes, the terminal 200 transmitsACK/NACKs using SR resources in all subframes in a period of the SRrepetition transmission. As a result, according to the presentembodiment, an SR need not be dropped if an ACK/NACK and the SR occur inthe same subframe as in FIG. 4A, thereby avoiding deterioration of SRdetection properties.

In addition, according to the present embodiment, a case in which“ACK/NACK repetition transmission occurs during SR repetitiontransmission” does not occur, and, as in the above case, deteriorationof the SR detection properties due to lack of in-phase combination atthe time of the detection of SRs can be avoided.

Second Embodiment

In the first embodiment, the ACK/NACK repetition transmission and the SRrepetition transmission through the PUCCH have been described. In thepresent embodiment, ACK/NACK repetition transmission and PUSCHrepetition transmission through the PUSCH will be described.

It is to be noted that basic configurations of a base station and aterminal according to the present embodiment are the same as thoseaccording to the first embodiment and will be described with referenceto FIG. 8 (base station 100) and FIG. 9 (terminal 200).

In the following description, as in the first embodiment, the number ofrepetitions of an ACK/NACK and the number of repetitions of a PUSCH arethe same.

The base station 100 sets, for the terminal 200, subframes (candidatesfor start positions) at which the ACK/NACK repetition transmissionstarts and subframes (candidates for start positions) at which the PUSCHrepetition transmission starts. The base station 100, for example, setsthe start positions of the ACK/NACK repetition transmission to the samesubframes for the start positions of the PUSCH repetition transmission.Alternatively, the base station 100 may set each of the start positionsof the ACK/NACK repetition transmission to one of the start positions ofthe PUSCH repetition transmission, or may set each of the startpositions of the PUSCH repetition transmission to one of the startpositions of the ACK/NACK repetition transmission.

The base station 100 (setting unit 101) then transmits timinginformation for identifying the set start positions of the ACK/NACKrepetition transmission and the set start positions of the PUSCHrepetition transmission to the terminal 200, for example, through higherlayer signaling.

For example, the base station 100 performs assignment (UL grant) of anuplink data signal using a downlink control channel (PDCCH) to theterminal 200. That is, the terminal 200 can identify a transmissiontiming of the uplink data signal on the basis of the assignment of theuplink data signal. As the timing information, therefore, existingcontrol information indicating the assignment of the uplink data signalmay be used, instead. In this case, the terminal 200 (settinginformation reception unit 209) may identify the start positions of thePUSCH repetition transmission on the basis of the timing information(the assignment of the uplink data signal: the existing controlinformation) and set part or all of the start positions of the PUSCHrepetition transmission as the start positions of the ACK/NACKrepetition transmission. The signaling for setting the start positionsof the ACK/NACK repetition transmission, therefore, becomes unnecessary.

Alternatively, the base station 100 may set arbitrary subframes as thestart positions of the PUSCH and ACK/NACK repetition transmission andtransmit timing information indicating the setting to the terminal 200.

The terminal 200 (setting information reception unit 209) sets the startpositions (subframes) of the ACK/NACK and PUSCH repetition transmissionon the basis of the timing information transmitted from the base station100. The terminal 200 (transmission unit 213) then repeatedly transmitsan ACK/NACK using consecutive subframes, which correspond to a certainnumber of repetitions, starting with a subframe that is a start positionof the ACK/NACK repetition transmission and a PUSCH using consecutivesubframes, which correspond to a certain number of repetitions, startingwith a subframe that is a start position of the PUSCH repetitiontransmission.

FIG. 11 illustrates an example of transmission timings of ACK/NACKs andPUSCHs. It is to be noted that in FIG. 11, the number of repetitions ofan ACK/NACK and a PUSCH is four (four subframes) each.

As illustrated in FIG. 11, in a subframe in which only an ACK/NACK istransmitted, the terminal 200 transmits the ACK/NACK using an ACK/NACKresource. In addition, in a subframe in which only data is transmitted,the terminal 200 transmits the data using a PUSCH.

In addition, as illustrated in FIG. 11, if ACK/NACK repetitiontransmission and PUSCH repetition transmission occur in the samesubframes, the terminal 200 time-multiplexes and transmits ACK/NACKs anddata in the PUSCH.

Here, the terminal 200 (setting information reception unit 209) setsstart positions of the ACK/NACK repetition transmission to the samesubframe for start positions of the PUSCH repetition transmission. Thatis, as illustrated in FIG. 11, the start positions of the ACK/NACKrepetition transmission are the same as the start positions of the PUSCHrepetition transmission.

In addition, as illustrated in FIG. 11, the number of repetitions of anACK/NACK and a PUSCH is the same, namely four subframes.

If ACK/NACK repetition transmission and PUSCH repetition transmissionoccur in the same subframes, therefore, subframes used for repeatedlytransmitting the ACK/NACK and subframes used for repeatedly transmittingthe PUSCH are the same. That is, if ACK/NACK repetition transmission andPUSCH repetition transmission occur in the same subframes, the terminal200 time-multiplexes and transmits the ACK/NACKs and the data usingPUSCHs in all subframes in a period of the ACK/NACK and data repetitiontransmission. In other words, in consecutive subframes (four consecutivesubframes in FIG. 11) in a period of the PUSCH repetition transmission,resources used for transmitting the ACK/NACKs do not switch or a signalin a PUSCH in the period of the ACK/NACK repetition transmission doesnot change as in FIG. 5.

As described above, according to the present embodiment, since thesignal repeatedly transmitted in the PUSCH does not change in the periodof the ACK/NACK repetition transmission as in FIG. 5, the base station100 can determine whether ACK/NACKs are included in PUSCHs afterreceiving a PUSCH repetition including data and an ACK/NACK the numberof times of ACK/NACK repetitions. As a result, deterioration of theACK/NACK decoding properties is likely to be avoided.

In addition, according to the present embodiment, a case in which “PUCCHrepetition transmission occurs during ACK/NACK repetition transmission”does not occur, and, as in the above case, deterioration of the ACK/NACKdecoding properties is likely to be avoided.

Third Embodiment

In the present embodiment, a case will be described in which startpositions of ACK/NACK repetition transmission and SR repetitiontransmission in the PUCCH are periodically set.

It is to be noted that basic configurations of a base station and aterminal according to the present embodiment are the same as thoseaccording to the first embodiment and will be described with referenceto FIG. 8 (base station 100) and FIG. 9 (terminal 200).

In the following description, as in the first embodiment, the number ofrepetitions of an ACK/NACK and the number of repetitions of a SR are thesame.

The base station 100 and the terminal 200 periodically set the startpositions (subframes) of the ACK/NACK repetition transmission and thestart positions (subframes) of the SR repetition transmission. The basestation 100 and the terminal 200, for example, set a period of the startpositions of the SR repetition transmission to an integral multiple of aperiod of the start positions of the ACK/NACK repetition transmission.Alternatively, the period of the start positions of the SR repetitiontransmission and the period of the start positions of the ACK/NACKrepetition transmission may be the same.

In addition, as in the first embodiment, the base station 100 and theterminal 200 match the start positions (subframes) of the SR repetitiontransmission with the start positions of the ACK/NACK repetitiontransmission. In addition, as in the first embodiment, if the ACK/NACKand SR transmission is in the same subframes, the terminal 200 transmitsACK/NACKs using SR resources.

FIG. 12 illustrates an example of transmission timings of ACK/NACKs andSRs according to the present embodiment.

In FIG. 12, the number of repetitions of an ACK/NACK and an SR is foureach.

In addition, as illustrated in FIG. 12, the period of the startpositions of the ACK/NACK repetition transmission is four subframes(that is, 4 ms), and the period of the start positions of the SRrepetition transmission is eight subframes (that is, 8 ms). That is, theperiod of the start positions of the SR repetition transmission is twice(an integral multiple of) the period of the start positions of theACK/NACK repetition transmission.

In addition, as illustrated in FIG. 12, the start positions (subframes)of the SR repetition transmission are matched with the start positionsof the ACK/NACK repetition transmission as in the first embodiment. Thatis, each of the subframes that are the start positions of the SRrepetition transmission is the same as one of the subframes that are thestart positions of the ACK/NACK repetition transmission. In addition, asillustrated in FIG. 12, if the ACK/NACK and SR transmission is in thesame subframes, ACK/NACKs are transmitted using SR resources as in thefirst embodiment.

The above-described start positions of the ACK/NACK repetitiontransmission are represented as subframes that satisfy the followingexpression.[Math. 1](10×n _(f) +└n _(s)/2┘)mod N _(ACK/NACK)=0  (1)

In Expression (1), n_(f) denotes a system frame number, n_(s) denotes aslot number in a frame, and N_(ACK/NACK) denotes the number of ACK/NACKrepetitions in the PUCCH. N_(ACK/NACK) is transmitted from the basestation 100 to the terminal 200 in advance, for example, as timinginformation. That is, the terminal 200 (setting information receptionunit 209) sets the start positions of the ACK/NACK repetitiontransmission in accordance with Expression (1) using the timinginformation transmitted from the base station 100.

On the other hand, the above-described start positions of the SRrepetition transmission are represented as subframes that satisfy thefollowing expression.[Math. 2](10×n _(f) +└n _(s)/2┘−N _(OFFSET,SR) ^(enhanced))mod SR _(PERIODICITY)^(enhanced)=0  (2)

SR_(PERIODICITY) ^(enhanced) and N_(OFFSET,SR) ^(enhanced) in Expression(2), however, are given in accordance with the following expression.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack & \; \\\left\{ \begin{matrix}{{SR_{PERIODICITY}^{enhanced}} = {N_{SR}SR_{PERIODICITY}}} \\{N_{{OFFSET},{SR}}^{enhanced} = {N_{SR}N_{{OFFSET},{SR}}}}\end{matrix} \right. & (3)\end{matrix}$

In Expression (3), N_(SR) denotes the number of SR repetitions, andN_(ACK/NACK)=N_(SR) in the present embodiment. In addition,SR_(PERIODICITY) and N_(OFFSET,SR) are defined by a table illustrated inFIG. 13 and calculated by a parameter I_(SR) transmitted from the basestation 100 to the terminal 200. That is, the terminal 200 (settinginformation reception unit 209) sets the start positions of the SRrepetition transmission in accordance with the table illustrated in FIG.13 and Expressions (2) and (3) using I_(SR) and N_(ACK/NACK)(=N_(SR))indicated in the timing information transmitted from the base station100.

FIG. 12, for example, illustrates an example in which the base station100 transmits N_(ACK/NACK)=N_(SR)=4 and I_(SR)=155 to the terminal 200.That is, since N_(SR)=N_(ACK/NACK) and, as illustrated in FIG. 13,SR_(PERIODICITY) is an integer, SR_(PERIODICITY)^(enhanced)(=SR_(PERIODICITY)N_(SR)) in Expression (2), which denotesthe period of the start positions of the SR repetition transmission, isan integral multiple of N_(ACK/NACK), which denotes the period of thestart positions of the ACK/NACK repetition transmission.

In the present embodiment, if there is an ACK/NACK to be transmitted ina subframe that is a start position of the ACK/NACK repetitiontransmission, the terminal 200 transmits the ACK/NACK using N_(ACK/NACK)consecutive subframes starting with the subframe that is the startposition of the ACK/NACK repetition transmission. In addition, if thereis an SR to be transmitted in a subframe that is a start position of theSR repetition transmission, the terminal 200 transmits the SR usingN_(SR) consecutive subframes starting with the subframe that is thestart position of the SR repetition transmission.

At this time, as in the first embodiment, the terminal 200 transmitsACK/NACKs using ACK/NACK resources in subframes in which ACK/NACKrepetitions are independently transmitted. In addition, the terminal 200transmits SRs using SR resources in subframes in which SR repetitionsare independently transmitted. On the other hand, the terminal 200transmits ACK/NACKs using SR resources in subframes in which SRrepetitions and ACK/NACK repetitions are simultaneously transmitted.

In doing so, as in the first embodiment, the start positions of the SRrepetition transmission are matched with the start positions of theACK/NACK repetition transmission. That is, the SR repetitiontransmission does not occur during the ACK/NACK repetition transmission,or the ACK/NACK repetition transmission does not occur in the period ofthe SR repetition transmission. Resources used for transmittingACK/NACKs therefore do not change during the SR repetition transmission.The base station 100 can thus decode the ACK/NACKs after receiving allof repeatedly transmitted SRs and determining whether the SRs have beentransmitted. As a result, deterioration of the ACK/NACK decodingproperties can be avoided.

Furthermore, as in the first embodiment, since the resources used fortransmitting the ACK/NACKs do not change in the period of the SRrepetition transmission, a signal point of the SR resources does notchange during the SR repetition transmission. In-phase combination cantherefore be performed at a time of detection of the SRs, therebyimproving the SR detection properties.

In addition, as in the first embodiment, if ACK/NACK repetitiontransmission and SR repetition transmission occur in the same subframes,the terminal 200 transmits ACK/NACKs using SR resources in all subframesin a period of the SR repetition transmission. As a result, an SR neednot be dropped if an ACK/NACK and the SR occur in the same subframe asin FIG. 4A, thereby avoiding deterioration of the SR detectionproperties.

In addition, as in the first embodiment, a case in which “ACK/NACKrepetition transmission occurs during SR repetition transmission” doesnot occur, and, as in the above case, deterioration of the SR detectionproperties due to lack of in-phase combination at the detection of SRscan be avoided.

Furthermore, in the present embodiment, since the start positions of theACK/NACK repetition transmission are set to predetermined periodicalsubframes, the system can be easily controlled in terms of the ACK/NACKrepetition transmission.

In addition, in the present embodiment, since the period of the startpositions of the SR repetition transmission is set to an integralmultiple of the period of the start positions of the ACK/NACK repetitiontransmission, the base station 100 can easily notify the terminal 200 ofthe start positions (subframes and a period) of the repetitiontransmission. In the present embodiment, for example, the terminal 200can identify the period N_(SR)(=N_(ACK/NACK)) of the start positions ofthe SR repetition transmission on the basis of the period N_(ACK/NACK)of the start positions of the ACK/NACK repetition transmission. Inaddition, the terminal 200 can calculate (Expressions (2) and (3)) thestart positions of the repetition transmission using the existingcorrespondence table (FIG. 13) just by receiving N_(ACK/NACK)(=N_(SR))and I_(SR) from the base station 100.

Fourth Embodiment

In the present embodiment, as in the third embodiment, a case will bedescribed in which start positions of ACK/NACK repetition transmissionand start positions of PUSCH repetition transmission in the PUSCH areperiodically set.

It is to be noted that basic configurations of a base station and aterminal according to the present embodiment are the same as thoseaccording to the first embodiment and will be described with referenceto FIG. 8 (base station 100) and FIG. 9 (terminal 200).

In the following description, as in the second embodiment, the number ofrepetitions of an ACK/NACK and the number of repetitions of a PUSCH arethe same.

The base station 100 and the terminal 200 periodically set the startpositions (subframes) of the ACK/NACK repetition transmission and thestart positions (subframes) of the PUSCH repetition transmission. Thebase station 100 and the terminal 200, for example, set a period of thestart positions of the ACK/NACK repetition transmission to be the sameas a period of the start positions of the PUSCH repetition transmission.Alternatively, either of the period of the start positions of theACK/NACK repetition transmission and the period of the start positionsof the PUSCH repetition transmission may be an integral multiple of theother.

In addition, as in the second embodiment, the base station 100 and theterminal 200 match the start positions (subframes) of the ACK/NACKrepetition transmission with the start positions of the PUSCH repetitiontransmission. In addition, as in the second embodiment, if the ACK/NACKand PUSCH transmission is in the same subframes, the terminal 200time-multiplexes and transmits ACK/NACKs and PUSCHs in the PUSCH.

FIG. 14 illustrates an example of transmission timings of ACK/NACKs andPUSCHs according to the present embodiment.

In FIG. 14, the number of repetitions of an ACK/NACK and a PUSCH is foureach.

In addition, as illustrated in FIG. 14, the period of the startpositions of the PUSCH repetition transmission is four subframes (thatis, 4 ms), and the period of the start positions of the ACK/NACKrepetition transmission, too, is four subframes (that is, 4 ms). Thatis, the period of the start positions of the ACK/NACK repetitiontransmission is the same as the period of the start positions of thePUSCH repetition transmission.

In addition, as illustrated in FIG. 14, the start positions (subframes)of the ACK/NACK repetition transmission are matched with the startpositions of the PUSCH repetition transmission as in the secondembodiment. That is, the subframes that are the start positions of theACK/NACK repetition transmission are the same as the subframes that arethe start positions of the PUSCH repetition transmission. In addition,as illustrated in FIG. 14, if the ACK/NACK and PUSCH transmission is inthe same subframes, ACK/NACKs and PUSCHs are time-multiplexed andtransmitted in the PUSCH as in the second embodiment. A method formultiplexing data and ACK/NACKs in the same subframes of the PUSCH isthe same as a conventional one.

The above-described start positions of the ACK/NACK repetitiontransmission are represented as subframes that satisfy the followingexpression.[Math. 4](10×n _(f) +└n _(s)/2┘)mod N _(ACK/NACK)=0  (4)

In Expression (4), n_(f) denotes a system frame number, n_(s) denotes aslot number in a frame, and N_(ACK/NACK) denotes the number of ACK/NACKrepetitions in the PUCCH. N_(ACK/NACK) is transmitted from the basestation 100 to the terminal 200 in advance, for example, as timinginformation. That is, the terminal 200 (setting information receptionunit 209) sets the start positions of the ACK/NACK repetitiontransmission in accordance with Expression (4) using the timinginformation transmitted from the base station 100.

On the other hand, the above-described start positions of the PUSCHrepetition transmission are represented as subframes that satisfy thefollowing expression.[Math. 5](10×n _(f) +└n _(s)/2┘)mod N _(PUSCH)=0  (5)

In Expression (5), N_(PUSCH) denotes the number of PUSCH repetitions,and N_(PUSCH)=N_(ACK/NACK) in the present embodiment. That is, theterminal 200 (setting information reception unit 209) can set the startpositions of the PUSCH repetition transmission in accordance withExpression (5) using the timing information (N_(ACK/NACK)(=N_(PUSCH)))regarding the ACK/NACK repetition transmission transmitted from the basestation 100.

FIG. 14, for example, illustrates an example in which the base station100 transmits N_(PUSCH)=N_(ACK/NACK)=4 to the terminal 200.

In the present embodiment, if there is an ACK/NACK to be transmitted ina subframe that is a start position of the ACK/NACK repetitiontransmission, the terminal 200 transmits the ACK/NACK using N_(ACK/NACK)consecutive subframes starting with the subframe that is the startposition of the ACK/NACK repetition transmission. In addition, if thereis data to be transmitted in a subframe that is a start position of thePUSCH repetition transmission, the terminal 200 transmits the data usingN_(PUSCH) consecutive subframes starting with the subframe that is thestart position of the PUSCH repetition transmission.

At this time, as in the second embodiment, the terminal 200 transmitsACK/NACKs using ACK/NACK resources in subframes in which ACK/NACKrepetitions are independently transmitted. In addition, the terminal 200transmits data using PUSCHs in subframes in which PUSCH repetitions areindependently transmitted. On the other hand, the terminal 200time-multiplexes and transmits ACK/NACKs and data in the PUSCH insubframes in which PUSCH repetitions and ACK/NACK repetitions aresimultaneously transmitted.

In doing so, as in the second embodiment, the ACK/NACK repetitiontransmission does not occur during the PUSCH repetition transmission,and a signal in the PUSCH does not change in a period of the PUSCHrepetition transmission. The base station 100 can therefore determinewhether ACK/NACKs are included in PUSCHs after receiving a PUSCHrepetition including data and an ACK/NACKs the number of times ofACK/NACK repetitions. As a result, deterioration of the ACK/NACKdecoding properties is likely to be avoided.

In addition, according to the present embodiment, a case in which “PUSCHrepetition transmission occurs during ACK/NACK repetition transmission”does not occur, and, as in the above case, deterioration of the ACK/NACKdecoding properties is likely to be avoided.

Furthermore, in the present embodiment, since the start positions of theACK/NACK repetition transmission and the PUSCH repetition transmissionare set to predetermined periodical subframes, the system can be easilycontrolled in terms of the ACK/NACK repetition transmission and thePUSCH repetition transmission.

In addition, in the present embodiment, since the period of the startpositions of the ACK/NACK repetition transmission is set to be the sameas the period of the start positions of the PUSCH repetitiontransmission, the base station 100 can easily notify the terminal 200 ofthe start positions (subframes and a period) of the repetitiontransmission. In the present embodiment, for example, the terminal 200can identify the period N_(ACK/NACK)(=N_(PUSCH)) of the start positionsof the ACK/NACK repetition transmission on the basis of the periodN_(PUSCH) of the start positions of the PUSCH repetition transmission.

Fifth Embodiment

In the first and third embodiments, cases in which the number ofrepetitions of an ACK/NACK and the number of repetitions of an SR in thePUCCH are the same have been described. The number of repetitions of anACK/NACK and the number of repetitions of an SR in the PUCCH, however,are not necessarily the same. In the present embodiment, therefore, acase will be described in which the number of repetitions of an ACK/NACKand the number of repetitions of an SR in the PUCCH are different fromeach other.

It is to be noted that basic configurations of a base station and aterminal according to the present embodiment are the same as thoseaccording to the first embodiment and will be described with referenceto FIG. 8 (base station 100) and FIG. 9 (terminal 200).

In FIG. 15, the number of repetitions of an ACK/NACK is four subframes,and the number of repetitions of an SR is eight subframes. That is, thenumber of repetitions of an SR is larger than the number of repetitionsof an ACK/NACK.

As illustrated in FIG. 15, if ACK/NACK repetition transmission and SRrepetition transmission occur in the same subframes, ACK/NACKs aretransmitted using SR resources in subframes (first four subframes) inwhich the ACK/NACKs and SRs are transmitted, and SRs are transmittedusing SR resources in other subframes (last four subframes) aftercompletion of the ACK/NACK repetition transmission. That is, if thenumber of repetitions of an SR is larger than the number of repetitionsof an ACK/NACK, a signal point of the SR resources might undesirablychange in midstream in a period of the SR repetition transmission (eightsubframes). If the signal point of the SR resources changes inmidstream, in-phase combination cannot be performed at a time ofdetection of SRs, thereby deteriorating the SR detection properties.

In the present embodiment, therefore, a method will be described bywhich deterioration of the SR detection properties can be avoided evenif the number of repetitions of an ACK/NACK and the number ofrepetitions of an SR in the PUCCH are different from each other, inaddition to the operations according to the first embodiment.

More specifically, if ACK/NACK repetition transmission and SR repetitiontransmission occur in the same subframes, the terminal 200 according tothe present embodiment sets the number of repetitions of an ACK/NACK inthe PUCCH to the number of repetitions of an SR or the number ofrepetitions of an ACK/NACK, whichever is larger.

In the example illustrated in FIG. 15, for example, the number ofrepetitions of an ACK/NACK is four subframes, and the number ofrepetitions of an SR is eight subframes. That is, the predeterminednumber of SR repetitions (eight subframes) is larger than thepredetermined number of ACK/NACK repetitions (four subframes). In thiscase, as illustrated in FIG. 16, if ACK/NACK repetition transmission andSR repetition transmission occur in the same subframes, the terminal 200repeatedly transmits an ACK/NACK the same number of times (eightsubframes) as the SR repetition transmission. That is, the number ofrepetitions of an ACK/NACK is set to the larger number (eight subframes)between the number of repetitions of an SR (eight subframes) and thenumber of repetitions of an ACK/NACK (four subframes).

In doing so, if ACK/NACK repetition transmission and SR repetitiontransmission simultaneously occur, ACK/NACKs are transmitted using SRresources in all subframes in a period of the SR repetitiontransmission. Since a signal point of the SR resources does not changein the period of the SR repetition transmission, the base station 100can detect SRs through in-phase combination, and it is likely thatdeterioration of the SR detection properties can be avoided.

In addition, in FIG. 16, if ACK/NACK repetition transmission and SRrepetition transmission simultaneously occur, the number of repetitionsof an ACK/NACK is increased and becomes the same as the number ofrepetitions of an SR, and the ACK/NACK decoding properties in the basestation 100 can be improved.

It is to be noted that in FIG. 16, a case in which the number ofrepetitions of an ACK/NACK is smaller than the number of repetitions ofan SR has been described. On the other hand, if the predetermined numberof repetitions of an ACK/NACK is larger than the predetermined number ofrepetitions of an SR, the terminal 200 uses the predetermined number ofrepetitions of an ACK/NACK. In doing so, even if ACK/NACK repetitiontransmission and SR repetition transmission simultaneously occur,ACK/NACKs are transmitted using SR resources at least in a period of theSR repetition transmission. A signal point of the SR resources thereforedoes not change in midstream, thereby avoiding deterioration of the SRdetection properties. On the other hand, a resource used fortransmitting an ACK/NACK in a period of the ACK/NACK repetitiontransmission switches from an SR resource to an ACK/NACK resource. Evenif the resource used for transmitting an ACK/NACK changes halfwaythrough the ACK/NACK repetition transmission, however, the base station100 can decode the ACK/NACKs without deteriorating the ACK/NACK decodingproperties using the ACK/NACKs transmitted using the SR resources in theperiod of the SR repetition transmission and the ACK/NACKs transmittedusing the ACK/NACK resources in periods other than the period of the SRrepetition transmission.

Sixth Embodiment

In the second and fourth embodiments, cases in which the number ofrepetitions of an ACK/NACK and the number of repetitions of a PUSCH(data) in the PUSCH are the same have been described. The number ofrepetitions of an ACK/NACK and the number of repetitions of data in thePUSCH, however, are not necessarily the same. In the present embodiment,therefore, as in the fifth embodiment, a case will be described in whichthe number of repetitions of an ACK/NACK and the number of repetitionsof data in the PUSCH are different from each other.

It is to be noted that basic configurations of a base station and aterminal according to the present embodiment are the same as thoseaccording to the first embodiment and will be described with referenceto FIG. 8 (base station 100) and FIG. 9 (terminal 200).

In FIG. 17, the number of repetitions of an ACK/NACK is four subframes,and the number of repetitions of a PUSCH (data) is eight subframes. Thatis, the number of repetitions of a PUSCH is larger than the number ofrepetitions of an ACK/NACK.

As illustrated in FIG. 17, if ACK/NACK repetition transmission and PUSCHrepetition transmission occur in the same subframes, ACK/NACKs and dataare time-multiplexed and transmitted in the PUSCH in subframes (firstfour subframes) in which the ACK/NACKs and the data are transmitted, andonly data is transmitted in the PUSCH in other subframes (last foursubframes) after completion of the ACK/NACK repetition transmission.That is, if the number of repetitions of a PUSCH is larger than thenumber of repetitions of an ACK/NACK, data content in the PUSCH mightundesirably change in a period of the PUSCH repetition transmission(eight subframes). If the data content in the PUSCH changes inmidstream, data decoding properties deteriorate, and the ACK/NACKdecoding properties also deteriorate.

In the present embodiment, therefore, a method will be described bywhich deterioration of the data decoding properties and the ACK/NACKdecoding properties can be avoided even if the number of repetitions ofan ACK/NACK and the number of repetitions of data in the PUSCH aredifferent from each other, in addition to the operations according tothe second embodiment.

More specifically, if ACK/NACK repetition transmission and PUSCHrepetition transmission occur in the same subframes, the terminal 200according to the present embodiment sets the number of repetitions of anACK/NACK in the PUSCH to the number of repetitions of a PUSCH or thenumber of repetitions of an ACK/NACK, whichever is larger.

In the example illustrated in FIG. 17, for example, the number ofrepetitions of an ACK/NACK is four subframes, and the number ofrepetitions of data is eight subframes. That is, the predeterminednumber of PUSCH repetitions (eight subframes) is larger than thepredetermined number of ACK/NACK repetitions (four subframes). In thiscase, as illustrated in FIG. 18, if ACK/NACK repetition transmission andPUSCH repetition transmission occur in the same subframes, the terminal200 repeatedly transmits an ACK/NACK the same number of times (eightsubframes) as the PUSCH repetition transmission. That is, the number ofrepetitions of an ACK/NACK is set to the larger number (eight subframes)between the number of repetitions of a PUSCH (eight subframes) and thenumber of repetitions of an ACK/NACK (four subframes).

In doing so, if ACK/NACK repetition transmission and PUSCH repetitiontransmission simultaneously occur, ACK/NACKs and data aretime-multiplexed and transmitted in the PUSCH in all subframes in aperiod of the PUSCH repetition transmission. Since data content in thePUSCH does not change in the period of the PUSCH repetitiontransmission, the base station 100 is likely to avoid deterioration ofPUSCH data decoding properties. The base station 100 is therefore alsolikely to avoid deterioration of the ACK/NACK decoding properties.

In addition, in FIG. 18, if ACK/NACK repetition transmission and PUSCHrepetition transmission simultaneously occur, the number of repetitionsof an ACK/NACK is increased and becomes the same as the number ofrepetitions of a PUSCH, and the ACK/NACK decoding properties in the basestation 100 can be improved.

It is to be noted that in FIG. 18, a case in which the number ofrepetitions of an ACK/NACK is smaller than the number of repetitions ofdata has been described. On the other hand, if the predetermined numberof repetitions of an ACK/NACK is larger than the predetermined number ofrepetitions of data, the terminal 200 uses the predetermined number ofrepetitions of an ACK/NACK. In doing so, even if ACK/NACK repetitiontransmission and PUSCH repetition transmission simultaneously occur,ACK/NACKs and data are time-multiplexed transmitted in the PUSCH atleast in a period of the PUSCH repetition transmission. Data content inthe PUSCH therefore does not change in midstream, thereby avoidingdeterioration of the data detection properties and the ACK/NACK decodingproperties. On the other hand, a resource used for transmitting anACK/NACK in a period of the ACK/NACK repetition transmission switchesfrom a PUSCH to an ACK/NACK resource in the PUCCH. Even if the resourceused for transmitting ACK/NACKs changes halfway through the ACK/NACKrepetition transmission, however, the base station 100 can decode theACK/NACKs without deteriorating the ACK/NACK decoding properties usingthe ACK/NACKs transmitted in the PUSCH in the period of the PUSCHrepetition transmission and the ACK/NACKs transmitted using the ACK/NACKresources in periods other than the period of the PUSCH repetitiontransmission.

The embodiments of the present disclosure have been described.

It is to be noted that although cases in which the present disclosure isconfigured by hardware have been taken as examples in the embodiments,the present disclosure can be implemented by software that cooperateswith hardware.

In addition, function blocks used to describe the embodiments areachieved as large-scale integration (LSI), which is typically anintegrated circuit. These may be separately achieved as chips, or someor all of these may be achieved as a chip. Although LSI has beenmentioned here, a term “integrated circuit (IC),” “system LSI,” “superLSI,” or “ultra LSI” might be used, instead, depending on a differencein a degree of integration.

In addition, a method for obtaining an integrated circuit is not limitedto LSI, but an integrated circuit may be achieved as a dedicated circuitor a general-purpose processor. A field-programmable gate array (FPGA)for which programming can be performed after an LSI is fabricated or areconfigurable processor capable of reconfiguring connections andsettings of circuit cells inside an LSI may be used, instead.

Furthermore, if a technique for obtaining an integrated circuit thatreplaces LSI appears as a result of evolution of semiconductortechnologies or from a different derivative technique, the functionblocks may be achieved as integrated circuits using the technique.Application of a biological technology is a possibility.

A terminal in the present disclosure includes a receiver that receivesinformation indicating a first subframe at which repetition transmissionof an uplink signal starts and a second subframe at which repetitiontransmission of a response signal for a downlink data signal starts, anda transmitter that repeatedly transmits the uplink signal using acertain number of consecutive subframes starting with the first subframeand the response signal using at least the certain number of consecutivesubframes starting with the second subframes. The first subframe is setto be the same as the second subframe.

In the terminal in the present disclosure, the first subframe and thesecond subframe are periodically set.

In the terminal in the present disclosure, a period of the firstsubframe is set to an integral multiple of a period of the secondsubframe.

In the terminal in the present disclosure, a period of the firstsubframe and a period of the second subframe are the same.

In the terminal in the present disclosure, a number of repetitionspredetermined for the response signal and a number of repetitionspredetermined for the uplink signal are the same.

In the terminal in the present disclosure, if a first number ofrepetitions predetermined for the response signal and a second number ofrepetitions predetermined for the uplink signal are different from eachother and the repetition transmission of the response signal and therepetition transmission of the uplink signal occur in the samesubframes, the number of repetitions of the response signal is set tothe first number of repetitions or the second number of repetitions,whichever is larger.

In the terminal in the present disclosure, the uplink signal is ascheduling request to a base station from the terminal. If therepetition transmission of the response signal and the repetitiontransmission of the scheduling request occur in the same subframes, thetransmitter transmits the response signal using a resource for thescheduling request.

In the terminal in the present disclosure, the uplink signal is anuplink data signal. If the repetition transmission of the responsesignal and the repetition transmission of the uplink data signal occurin the same subframes, the transmitter time-multiplexes and transmitsthe response signal and the uplink data signal in an uplink datachannel.

A base station in the present disclosure includes a setter thatgenerates control information for identifying a first subframe at whichrepetition transmission of an uplink signal starts and a second subframeat which repetition transmission of a response signal for a downlinkdata signal starts, and a receiver that receives, from a terminal thathas received the control information, the uplink signal repeatedlytransmitted using a certain number of consecutive subframes startingwith the first subframe and the response signal repeatedly transmittedusing at least the certain number of consecutive subframes starting withthe second subframe. The setter sets the first subframe to be the sameas the second subframe.

A transmission method in the present disclosure includes receivinginformation indicating a first subframe at which repetition transmissionof an uplink signal starts and a second subframe at which repetitiontransmission of a response signal for a downlink data signal starts, andrepeatedly transmitting the uplink signal using a certain number ofconsecutive subframes starting with the first subframe and the responsesignal using at least the certain number of consecutive subframesstarting with the second subframe. The first subframe is set to be thesame as the second subframe.

A reception method in the present disclosure includes generating controlinformation for identifying a first subframe at which repetitiontransmission of an uplink signal starts and a second subframe at whichrepetition transmission of a response signal for a downlink data signalstarts, and receiving, from a terminal that has received the controlinformation, the uplink signal repeatedly transmitted using a certainnumber of consecutive subframes starting with the first subframe and theresponse signal repeatedly transmitted using at least the certain numberof consecutive subframes starting with the second subframe. In thegenerating, the first subframe is set to be the same as the secondsubframe.

Disclosures in the specification, drawings, and abstract included inJapanese Patent Application No. 2014-017133 filed Jan. 31, 2014 are allused to assist the present application.

The present disclosure is useful in a mobile communication system.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

The invention claimed is:
 1. A communication apparatus comprising: areceiver which, in operation, receives a downlink data signal andcontrol information indicating a starting position; and a transmitterwhich, in operation, repeatedly transmits both anAcknowledgement/Negative Acknowledgement (ACK/NACK) signal related tothe downlink data signal, and one or more other signals different fromthe ACK/NACK signal, which are mapped to consecutive time resourcesstarting from the starting position, wherein, both the ACK/NACK signaland the one or more other signals are transmitted in a Physical UplinkShared Channel (PUSCH), and both the ACK/NACK signal and the one or moreother signals are repeated in each of the consecutive time resources. 2.The communication apparatus according to claim 1, wherein the controlinformation is indicated via a Physical Downlink Control Channel(PDCCH).
 3. The communication apparatus according to claim 1, whereinthe control information indicates the starting position of atransmission of the ACK/NACK signal.
 4. The communication apparatusaccording to claim 1, wherein frequency resources of the PUSCH are thesame regardless of a value of the one or more other signals.
 5. Thecommunication apparatus according to claim 1, wherein the time resourceis a subframe.
 6. A communication method comprising: receiving adownlink data signal and control information indicating a startingposition; and repeatedly transmitting both an Acknowledgment/NegativeAcknowledgement (ACK/NACK) signal related to the downlink data signal,and one or more other signals different from the ACK/NACK signal, whichare mapped to consecutive time resources starting from the startingposition, wherein both the ACK/NACK signal and the one or more othersignals are transmitted in a Physical Uplink Shared Channel (PUSCH), andboth the ACK/NACK signal and the one or more other signals are repeatedin each of the consecutive time resources.
 7. The communication methodaccording to claim 6, wherein the control information is indicated via aPhysical Downlink Control Channel (PDCCH).
 8. The communication methodaccording to claim 6, wherein the control information indicates thestarting position of a transmission of the ACK/NACK signal.
 9. Thecommunication method according to claim 6, wherein frequency resourcesof the PUSCH are the same regardless of a value of the one or more othersignals.
 10. The communication method according to claim 6, wherein thetime resource is a subframe.